A number of disease conditions are associated with the action of bacteria in the oral cavity. Dental plaque is a soft deposit that forms on the surface of the teeth as a by-product of bacterial growth. Gingivitis, an inflammation or infection of the gums and alveolar bones, is generally believed to be caused by plaque causing bacteria and the toxins formed as by-products from the bacteria. In addition, plaque provides a locus for calculus or tartar formation. Periodontitis is generally believed to occur where unremoved plaque hardens into calculus (tartar), which affects the periodontal ligaments. As plaque and tartar continue to build up, the gums begin to recede, which can lead to continued infection and potentially the loss of teeth.
To prevent or treat these diseased conditions, antibacterial agents are incorporated into oral care compositions such as toothpaste and mouthwashes or rinses. Application of antibacterial compositions in the oral cavity tends to retard plaque formation and related oral infections.
The antiplaque efficacy of antibacterial compounds in a dentifrice composition depends on a number of factors, including the presence of other ingredients that may interfere with its action. For example, certain cationic antibacterial compounds and certain nonionic antibacterial compounds lose their effectiveness when formulated with certain anionic surfactants or other anionic active ingredients, such as tartar control phosphates. In many instances, it is preferred to use antibacterial compounds that do not show the adverse interactions with such anionic components.
Some substituted phenols and biphenols are known to have antimicrobial properties. Natural products such as eugenol (4-allyl-2-methoxyphenol) have been used in oral care as a pulp capping agent and root canal sealer. It is generally recognized as safe by the FDA. A dimer of eugenol, dehydrodieugenol, is reported to be less cytotoxic and have greater anti-inflammatory activity than eugenol. There is an ongoing need to find biphenol compounds with acceptable combinations of antibacterial activity and safety.